The downtown Los Angele skyline is seen from Griffith Observatory on July 1, 2019. In a letter to Mary Nichols, chairwoman of the California Air Resources Board, the Environmental Protection Agency said the federal and state governments “have made great progress” toward resolving the backlog of “outdated, unnecessary or deficient” reports on the state's plans to combat pollutants

Photo: Christina House / TNS

WASHINGTON — The Trump administration appears to have softened its threat to withhold California’s federal highway funding over a backlog of air-pollution control plans.

Environmental Protection Agency Regional Administrator Michael Stoker said in a letter dated Dec. 30 to California’s top air-quality official that the federal and state governments “have made great progress” to reduce a backlog of reports mandated under the Clean Air Act.

The letter, first reported Monday by McClatchy news service, is an unexpected sign of cooperation between the EPA and California’s Air Resources Board as they battle over pollution standards.

In September, the EPA accused California officials of failing to submit pollution-reduction plans required under federal law. The agency said that if the state didn’t fix the problem, the Trump administration could freeze funding for highway projects.

The EPA said the state is responsible for a “disproportionate share” of backlogged State Implementation Plans, blueprints for how states will improve air quality.

But Stoker, in his recent letter to California Air Resources Board Chairwoman Mary Nichols, said the state has made “significant” progress by withdrawing 43 of its 130 pollution reports because they were “outdated, unnecessary or deficient.”

“Through our mutual commitments, I hope to either approve or have withdrawn all California (air-quality plans) in the very near future,” Stoker wrote. “Of course, the next step will be to develop replacement (plans) that protect human health and the environment.”

A spokeswoman for the Air Resources Board said it “has been helping U.S. EPA to resolve its administrative backlog for years,” adding that this “ongoing work is nothing new.”

California officials had previously called the EPA’s funding threat politically motivated. In September, Gov. Gavin Newsom said it was “a threat of pure retaliation.”

The EPA’s warning came as President Trump and California leaders clashed over climate change policy, a separate but related fight. Last fall, Trump moved to revoke the state’s decades-old waiver to adopt stricter vehicle emissions standards.

California officials have filed multiple lawsuits fighting the decision, arguing it will harm the health of tens of millions of people already living with poor air quality.

Dustin Gardiner is a state Capitol reporter for The San Francisco Chronicle. He joined The Chronicle in 2019, after nearly a decade with The Arizona Republic, where he covered state and city politics. Dustin won several awards for his reporting in Arizona, including the 2019 John Kolbe Politics Reporting award, and the 2017 Story of the Year award from the Arizona Newspapers Association. Outside of work, he enjoys hiking, camping, reading fiction and playing Settlers of Catan. He's a member of NLGJA, the association of LGBTQ journalists.